In recent years, it has been considered to be important to elevate awareness of global environmental issues, and take measures against global warming, and it has been desired to clean automotive exhaust gas due to its effects on the environment. It is known that the capability to clean automotive exhaust gas is affected by the exhaust gas purification performance of automobiles and the composition of gasoline. In particular, the petroleum refining industry is required to provide high-quality gasoline.
Gasoline is produced by blending a plurality of gasoline blend stocks obtained by a crude oil refining process. In particular, a gasoline fraction obtained by subjecting a heavy hydrocarbon oil to a fluid catalytic cracking reaction (hereinafter appropriately referred to as “FCC gasoline”) is incorporated in gasoline in large quantities, and considerably affects the quality of gasoline.
The heavy hydrocarbon oil catalytic cracking reaction is a reaction that converts a low-quality heavy oil obtained by a petroleum refining process into a light hydrocarbon oil through catalytic cracking. When producing FCC gasoline, hydrogen, coke, liquid petroleum gas (LPG), light cycle oil (LCO) (i.e., middle distillate), as well as heavy cycle oil (HCO) and slurry oil (SLO) (i.e., heavy distillate) are produced as by-products.
Therefore, a fluid catalytic cracking catalyst (hereinafter appropriately referred to as “FCC catalyst”) has been desired that exhibits high cracking activity with respect to a heavy hydrocarbon oil, increases the yield of FCC gasoline, can produce high-quality FCC gasoline having a high octane number, and can efficiently produce FCC gasoline.
In recent years, it has become necessary to subject a heavy hydrocarbon oil having a high heavy metal (e.g., vanadium and nickel) content and a high residual carbon content to fluid catalytic cracking along with the use of heavy low-quality crude oil.
If vanadium is deposited on the FCC catalyst, the structure of the zeolite that is used as the active component of the FCC catalyst is destroyed, whereby the activity of the catalyst significantly deteriorates, and the amount of hydrogen/coke produced increases. As a result, the selectivity of gasoline (i.e., the yield of FCC gasoline) decreases, for example.
If nickel is deposited on the surface of the FCC catalyst, a dehydrogenation reaction is promoted, whereby the amount of hydrogen/coke produced increases. As a result, the selectivity of gasoline (i.e., the yield of FCC gasoline) decreases, for example.
Development of a catalyst that exhibits excellent cracking activity has been desired in order to deal with the use of heavy low-quality crude oil. For example, the applicant of the present application proposed an FCC catalyst that includes phosphorus (see Patent Document 1 (JP-A-2010-247146), for example).